Process for producing photoresist polymeric compounds

ABSTRACT

Process for producing photoresist polymeric compound having repeated units corresponding to at least one monomer selected from monomer (a) having lactone skeleton, monomer (b) having group which becomes soluble in alkali by elimination with acid, and monomer (c) having alicyclic skeleton having hydroxyl group. Process includes (A) polymerizing mixture of monomers containing at least one monomer selected from the above monomers (a), (b), and (c), and (B) extracting polymer formed in the polymerization by using organic solvent and water to partition the formed polymer into organic solvent layer and metal component impurity into aqueous layer, or passing polymer solution, which contains polymer having repeated units corresponding to at least one of the above monomers (a), (b), and (c) and metal content of which is 1000 ppb by weight or less relative to the polymer through filter comprising porous polyolefin membrane having cation-exchange group. The photoresist polymeric compounds have a metallic impurity content that is extremely low.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a 37 C.F.R. §1.53(b) divisional of U.S.application Ser. No. 11/335,580 filed Jan. 20, 2006, now U.S. Pat. No.7,662,897 which is a 37 C.F.R. §1.53(b) divisional of U.S. applicationSer. No. 10/476,211 filed on Oct. 28, 2003, now U.S. Pat. No. 7,015,291which is the National Phase of PCT International Application No.PCT/JP03/03058 filed on Mar. 14, 2003, which in turn claims priority onJapanese Application Nos. 2002-098840 and 2002-098841, both of whichwere filed on Apr. 1, 2002. The entire contents of each of the aboveapplications is hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to a process for producing a photoresistpolymeric compound that is useful to prepare a photoresist-resincomposition applied for a micro processing of semiconductor and others.

BACKGROUND ART

Positive photoresist used in a process for producing semiconductors mustconcurrently have different characteristics such as a property that anexposed portions becomes soluble in alkali by light irradiation, anability of adhesion to silicon wafers, plasma-etching resistance, andtransparency to used light. The positive photoresist is generally usedas a solution containing a base component polymer, a light-activatableacid generator, and some sorts of additives for controlling the abovecharacteristics. On the other hand, a wavelength of a light source oflithography used for manufacturing semiconductors has become shorterfrom year to year and the ArF excimer laser with a wavelength of 193 nmis promising as a next-generation light source. As a photoresist polymerused in the ArF excimer laser exposure system, various polymers havingrepeated units containing a lactone skeleton that exhibit high adhesionto substrates and an alicyclic hydrocarbon skeleton that exhibits highetching resistance have been proposed.

These polymers are ordinarily isolated by polymerizing a mixture ofmonomers, and subjecting the polymer solution to be allowed toprecipitation procedure. There is, however, a problem that a requiredcapability (sensitivity and others) isn't performed because ofcontaining an impurity such as metal component in the resulting polymerwhen the polymer is used as a photoresist resin component. Particularly,when metal components such as sodium and iron are contained, anelectrical characteristic of semiconductors declines. There is also aproblem that a polymer is hard to be dissolved in a resist solventbecause surface of the polymer particles become hard or the polymerparticles are welded to each other.

DISCLOSURE OF INVENTION

Accordingly, an object of the present invention is to provide a processfor effectively producing a photoresist polymeric compound in which acontent of impurities such as a metal component or others is extremelylow.

Another object of the present invention is to provide a process foreffectively producing a photoresist polymeric compound, which is easilyand certainly dissolved in a resist solvent in addition to the abovepoint.

Still another object of the present invention is to provide a processfor producing a photoresist polymeric compound, which don't exert a badinfluence upon an electrical characteristic of semiconductor and so onin case of using as a resin component in a photoresist resin compound.

The present inventors made intensive investigations to achieve the aboveobjects, and found that, when a photoresist polymer is treated byextraction procedure using an organic solvent and water, or a polymersolution containing a photoresist polymer and being metal content of aspecific amount or less is passed through a filter constituted by aspecific porous polyolefin membrane, metal components, which exert a badinfluence upon a resist performance and an electrical characteristic ofsemiconductor can be removed easily. The present invention was completedbased on the above information.

Specifically, the present invention is to provide a process forproducing a photoresist polymeric compound, which have a repeated unitcorresponding to at least one monomer selected from a monomer (a) havinga lactone skeleton, a monomer (b) having a group, which becomes solublein alkali by elimination with an acid and a monomer (c) having analicyclic skeleton having a hydroxyl group,

which process comprises the step of;

(i) the polymerization step (A) of subjecting a mixture of monomerscontaining at least one monomer selected from the above monomers (a),(b) and (c) to polymerization, and the extraction step (B) of subjectingthe polymer formed in the polymerization to extraction procedure usingan organic solvent and water to partition the formed polymer into anorganic solvent layer and a metal component as an impurity into anaqueous layer, or

(ii) the step (I) of passing a polymer solution, which contains apolymer having a repeated unit corresponding to at least one of theabove monomers (a), (b) and (c), and a metal content of which is 1000ppb by weight or less relative to the polymer, through a filterconstituted by a porous polyolefin membrane having cation-exchangegroup.

The monomer (a) having a lactone skeleton includes (meth)acrylic acidester monomers represented by the following formulae (1a), (1b) and(1c):

wherein R¹ is a group including (meth)acryloyloxy group, each of R², R³and R⁴ is a lower alkyl group, n denotes an integer of 0 to 3, and mdenotes an integer of 0 to 5.

The monomer (b) having a group which becomes soluble in alkali byelimination with an acid includes (meth)acrylic acid ester monomersrepresented by the following formulae (2a) and (2b):

wherein R is a hydrogen atom or a methyl group, R⁵ is a hydrogen atom ora lower alkyl group, each of R⁶, R⁷, R⁸ and R⁹ is a lower alkyl group,and n denotes an integer of 0 to 3.

The monomer (c) having an alicyclic skeleton having a hydroxyl groupincludes (meth)acrylic acid ester monomers represented by the followingformula (3a):

wherein R is a hydrogen atom or a methyl group, R¹⁰ is a methyl group, ahydroxyl group, an oxo group or a carboxyl group and k denotes aninteger of 1 to 3, where at least one of the k R¹⁰s is a hydroxyl group.

The polymerization step (A) may comprise the step of polymerizing amixture of monomers in a glycol or ester solvent by droppingpolymerization method.

The extraction step (B) may comprise the step of adding an organicsolvent having a specific gravity of 0.95 or less and water into apolymerization solution obtained in a polymerization step (A) topartition a formed polymer into an organic solvent layer and a metalcomponent as an impurity into an aqueous layer. Further, the extractionstep (B) may comprise the step of extracting by adding an organicsolvent having a specific gravity of 0.95 or less and a solubilityparameter (SP value) of 20 MPa^(1/2) or less and water in a glycol orester solvent solution of a polymer formed by polymerization, and topartition the formed polymer into an organic solvent layer and a metalcomponent as an impurity into a aqueous layer.

The process of the present invention may further comprise aprecipitation purification step (C) of precipitating or re-precipitatinga polymer formed by polymerization. The precipitation purification step(C) may comprise the step of precipitating or re-precipitating a polymerby adding a solution containing a polymer formed by polymerization andglycol or ester solvent into a solvent containing at least ahydrocarbon.

The process of the present invention may comprise the repulping step (D)of repulping a polymer formed by polymerization with a solvent. Ahydrocarbon solvent can be used as a repulping solvent.

The process of the present invention may comprise the rinsing step (E)of rinsing a polymer formed by polymerization with a solvent. Ahydrocarbon solvent and/or water such as super-pure water can be used asa rinsing solvent.

The process of the present invention may comprise the drying step (F) ofdrying the resulting polymer (the recovered precipitate) after thepolymer formed by polymerization is subjected to precipitationpurification. Further, the process of the present invention may comprisethe redissolving step (G) of redissolving the resulting polymer (therecovered precipitate) in an organic solvent to prepare a polymersolution after the polymer formed by polymerization is subjected toprecipitation purification. At least one solvent selected from a glycolsolvent, an ester solvent and a ketone solvent can be used as aredissolving solvent. In addition, the process of the present inventionmay comprise the evaporating step (H) wherein a photoresist-polymersolution is prepared by concentrating a polymer solution obtained byredissolving in an organic solvent to remove a low-boiling-pointsolvent.

The process of the present invention may comprise the filtration step(J) wherein insolubles are removed by filtrating a polymer solutioncontaining a polymer having a repeated unit corresponding to at leastone monomer selected from the monomers (a), (b) and (c) before the step(I).

The process of the present invention may comprise the water washingtreatment step (K) wherein a metal content in a polymer solution isreduced by washing a polymer solution containing a polymer having arepeated unit corresponding to at least one monomer selected from themonomers (a), (b) and (c) with water before the step (I).

In the present description, the term “metal content” means a totalcontent (as metal) of Na, Mg, Al, K, Ca, Cr, Mn, Fe, Ni, Cu and Zn onthe basis of a polymer.

BEST MODE FOR CARRYING OUT THE INVENTION

[Polymerization Step (A)]

In the polymerization step (A), a mixture of monomers (even when amonomer is single sort, “a mixture of monomers” is used for the sake ofconvenience) containing at least one monomer selected from a monomer (a)having a lactone skeleton, a monomer (b) containing a group whichbecomes soluble in alkali by elimination with an acid and a monomer (c)having an alicyclic skeleton containing a hydroxyl group is treated in apolymerization to form a polymer.

The monomer (a) having a lactone skeleton gives substrate-adhesivefunction to a polymer. Further, depending on a structure, anacid-cleavage function (alkali-soluble function) may be given to apolymer (a repeated unit having β-(meth)acryloyloxy-γ-butyrolactone andso on). A lactone skeleton isn't limited particularly and, for example,about 4 to 20 membered lactone skeleton is represented. A lactoneskeleton may be a single ring of only a lactone ring and may be apolycyclic ring made by condensation of a non-aromatic or aromaticcarbon ring or hetero ring. Typical lactone skeletons are3-oxatricyclo[4.2.1.0^(4,8)]nonane-2-one ring(=2-oxatricyclo[4.2.1.0^(4,8)]nonane-3-one ring),3-oxatricyclo[4.3.1.1^(4,8)]undecane-2-one ring, γ-butyrolactone ring,δ-valerolactone ring, ε-caprolactone and so on. In many case, a lactoneskeleton combines with a carbon atom constituting a backbone of polymerthrough an ester bond or an ester bond and a connecting group such analkylene group.

Typical examples of the monomer (a) having a lactone skeleton are(meth)acrylic acid ester monomers represented by the above formulae(1a), (1b) and (1c). Wherein each of R¹, R², R³ and R⁴ is a groupbonding to a ring and R¹ is a group having (meth)acryloyloxy group, eachof R², R³ and R⁴ is a lower alkyl group, n denotes an integer of 0 to 3and m denotes an integer of 0 to 5. The group having the said(meth)acryloyloxy group includes, for example, (meth)acryloyloxy group;(meth)acryloyloxy alkyl group such as (meth)acryloyloxy methyl group and(meth)acryloyloxy ethyl group. In many case, R¹ bonds to the 5thposition of 3-oxatricyclo[4.3.1.0^(4,8)]nonane-2-one ring in the formula(1a), to the 6th position of 3-oxatricyclo[4.2.1.1^(4,8)]undecane-2-onering in the formula (1b) and to the a position or the β position ofγ-butyrolactone ring in the formula (1c).

The lower alkyl groups in R², R³ and R⁴ include, for example, C₁₋₄ alkylgroups such as methyl, ethyl, isopropyl, propyl, butyl, isobutyl,s-butyl and t-butyl group. The preferable lower alkyl group includesmethyl group and ethyl group, and methyl group is particularlypreferable.

In the (meth)acrylic acid ester represented by the above formula (1a),the n R²s may be the same group or different from each other. In manycase, R² bonds to a carbon atom of a bridge head position.

As the typical examples of the (meth)acrylic acid ester monomerrepresented by the formula (1a), there may be mentioned5-acryloyloxy-3-oxatricyclo[4.2.1.0^(4,8)]nonane-2-one(=9-acryloyloxy-2-oxatricyclo[4.2.1.0^(4,8)]nonane-3-one=5-acryloyloxy-2,6-norbornanecarbolactone),5-methacryloyloxy-3-oxatricyclo[4.2.1.0^(4,8)]nonane-2-one(=9-methacryloyloxy-2-oxatricyclo[4.2.1.0^(4,8)]nonane-3-one=5-methacryloyloxy-2,6-norbornanecarbolactone) and so on.

In the (meth)acrylic acid ester monomer represented by the above formula(1b), the n R³s may be the same group or different from each other. Inmany case, R³ bonds to a carbon atom of a bridge head position.

As the typical examples of the (meth)acrylic acid ester monomerrepresented by the formula (1b), there may be mentioned6-acryloyloxy-3-oxatricyclo[4.3.1.1^(4,8)]undecane-2-one,6-methacryloyloxy-3-oxatricyclo[4.3.1.1^(4,8)]undecane-2-one and so on.

In the (meth)acrylic acid ester monomer represented by the above formula(1c), the m R⁴s may be the same group or different from each other.Preferably, m is about 0 to 3.

As the typical examples of the (meth)acrylic acid ester monomerrepresented by the formula (1c), there may be mentioned, for example,α-(meth)acryloyloxy-γ-butyrolactones such asα-acryloyloxy-γ-butyrolactone, α-acryloyloxy-α-methyl-γ-butyrolactone,α-acryloyloxy-β,β-dimethyl-γ-butyrolactone,α-acryloyloxy-α,β,β-trimethyl-γ-butyrolactone,α-acryloyloxy-γ,γ-dimethyl-γ-butyrolactone,α-acryloyloxy-α,γ,γ-trimethyl-γ-butyrolactone,α-acryloyloxy-β,β,γ,γ-tetramethyl-γ-butyrolactone,α-acryloyloxy-α,β,β,γ,γ-pentamethyl-γ-butyrolactone,α-methacryloyloxy-γ-butyrolactone,α-methacryloyloxy-α-methyl-γ-butyrolactone,α-methacryloyloxy-β,β-dimethyl-γ-butyrolactone,α-methacryloyloxy-α,β,β-trimethyl-γ-butyrolactone,α-methacryloyloxy-γ,γ-dimethyl-γ-butyrolactone,α-methacryloyloxy-α,γ,γ-trimethyl-γ-butyrolactone,α-methacryloyloxy-β,β,γ,γ-tetramethyl-γ-butyrolactone andα-methacryloyloxy-α,β,β,γ,γ-pentamethyl-γ-butyrolactone; aβ-(meth)acryloyloxy-γ-butyrolactones such asβ-acryloyloxy-γ-butyrolactone and β-methacryloyloxy-γ-butyrolactone.

The compounds represented by the above formulae (1a), (1b) and (1c) canbe obtained by subjecting a corresponding alcohol compounds and(meth)acrylic acid or its reactive derivative to a conventionalesterification reaction.

The monomer (b) containing a group, which becomes soluble in alkali byelimination with an acid, gives a polymer an alkali-soluble function. Astypical examples of the monomer (b) having a group which becomes solublein alkali by elimination with an acid, there may be mentioned(meth)acrylic acid ester monomers represented by the above formulae (2a)or (2b). In the formulae, R is a hydrogen atom or a methyl group, R⁵ isa hydrogen atom or a lower alkyl group, each of R⁶, R⁷, R⁸ and R⁹ is alower alkyl group and n denotes an integer of 0 to 3. Each of R⁷ and R⁹is a group bonding to a ring. As the lower alkyl group, there may bementioned the same groups as defined above.

In the (meth)acrylic acid ester monomers represented by the aboveformula (2a), the n R⁷s may be the same group or different from eachother. In many case, R⁷ bonds to a carbon atom of a bridge headposition.

As the typical examples of the (meth)acrylic acid ester monomersrepresented by the formula (2a), there may be mentioned, for example,1-(1-acryloyloxy-1-methylethyl)adamantane,1-(1-acryloyloxy-1-methylethyl)-3,5-dimethyladamantane,1-(1-methacryloyloxy-1-methylethyl)adamantane,1-(1-methacryloyloxy-1-methylethyl)-3,5-dimethyladamantane and others.

In the (meth)acrylic acid ester monomers represented by the aboveformula (2b), the n R⁹s may be the same group or different from eachother. In many case, R⁹ bonds to a carbon atom of a bridge headposition.

As the typical examples of the (meth)acrylic acid ester monomersrepresented by the formula (2b), there may be mentioned, for example,2-acryloyloxy-2-methyladamantane,2-acryloyloxy-2,5,7-trimethyladamantane,2-methacryloyloxy-2-methyladamantane,2-methacryloyloxy-2,5,7-trimethyladamantane and others.

The monomer (c) including an alicyclic skeleton having a hydroxyl groupgives a polymer an etching resistance and substrate-adhesive function.The alicyclic hydrocarbon group may be a single-ring hydrocarbon groupor a multi-ring (bridged-ring) hydrocarbon group. As the typicalexamples of the monomer (c) including an alicyclic skeleton having ahydroxyl group, there may be mentioned the (meth)acrylic ester monomersrepresented by the formula (3a). In the formula, R is a hydrogen atom ora methyl group; R¹⁰ is a substituent bonding to a ring and shows amethyl group, a hydroxyl group, an oxo group or a carboxyl group. kdenotes an integer of 1 to 3. The k R¹⁰s may be the same group ordifferent from each other. At least one of the k R¹⁰s is a hydroxylgroup. In many case, R¹⁰ bonds to a carbon atom of a bridge headposition.

As the typical examples of the (meth)acrylic acid ester monomersrepresented by the formula (3a), there may be mentioned, for example,1-acryloyloxy-3-hydroxy-5,7-dimethyladamantane,1-hydroxy-3-methacryloyloxy-5,7-dimethyladamantane,1-acryloyloxy-3-hydroxyadamantane,1-hydroxy-3-methacryloyloxyadamantane,1-acryloyloxy-3,5-dihydroxyadamantane,1,3-dihydroxy-5-methacryloyloxyadamantane and others.

As a monomer employed in a polymerization, at least one of the abovemonomers (a), (b) and (c), preferably two or more of the above threesorts, and particularly three sorts of monomers may be used. Further, ifnecessary, other monomer may be subjected to co-polymerization.Polymerization may be performed by common methods such as a solutionpolymerization and a bulk polymerization.

For a polymerization solvent, solvents employed commonly in apolymerization of an acrylic monomer or an olefin monomer may besuitable and there may be mentioned, for example, a glycol solvent, anester solvent, a ketone solvent, an ether solvent or a mixed solventthereof. The glycol solvent includes, for example, propylene glycolssolvent such as propylene glycol monomethyl ether, propylene glycolmonomethyl ether acetate; ethylene glycols solvent such as ethyleneglycol monomethyl ether, ethylene glycol monomethyl ether acetate,ethylene glycol monoethyl ether, ethylene glycol monoethyl etheracetate, ethylene glycol monobutyl ether, ethylene glycol monobutylether acetate; and so on. As the ester solvent, there may be mentionedlactic acid esters solvent such as ethyl lactate; propionic acid esterssolvent such as methyl 3-methoxypropionionate; acetic acid esterssolvent such as methyl acetate, ethyl acetate, propyl acetate and butylacetate; and so on. The ketone solvent includes acetone, methyl ethylketone, methyl isobutyl ketone, methyl amyl ketone, cyclohexanone andothers. The ether solvent includes diethyl ether, diisopropyl ether,dibutyl ether, tetrahydrofuran, dioxane and others.

A preferable polymerization solvent includes glycols solvent such aspropylene glycol monomethyl ether and propylene glycol monomethyl etheracetate, ester solvents such as ethyl lactate, ketones solvent such asmethyl isobutyl ketone and methyl amyl ketone, and a mixed solventthereof. Particularly, solvents containing at least propylene glycolmonomethyl ether acetate such as a single solvent of propylene glycolmonomethyl ether acetate, a mixed solvent of propylene glycol monomethylether acetate and propylene glycol monomethyl ether, and a mixed solventof propylene glycol monomethyl ether acetate and ethyl lactate arepreferred.

As a polymerization method, dropping polymerization is suitablyemployed. The dropping polymerization is the method performing apolymerization by dropping or adding a monomer (solution) and/or apolymerization initiator (solution) successively into a reactor. Thedropping polymerization provides a polymer having uniformco-polymerization composition obtained at the first stage ofpolymerization with that obtained at the latter stage thereof. A knownpolymerization initiator can be used. A polymerization temperature is,for example, from 40° C. to 150° C. and preferably from about 60° C. to120° C.

An obtained polymerization solution (polymer dope) may be treated in thefiltration step to remove impurities. A pore size of a filtrationmaterial used in a filtration is, for example, 1 μm or less andpreferably 0.8 μm or less.

[Extraction Step (B)]

In the extraction step (B), a polymer formed by polymerization istreated in an extraction procedure (washing procedure) using an organicsolvent and water, and the formed polymer is partitioned into an organicsolvent layer and a metal element as impurities is partitioned into anaqueous layer. By this step, a metal element badly affecting to a resistperformance can be effectively removed from a polymer. A treatedmaterial treated in the extraction step (B) can be a polymer formed bypolymerization or a solution containing the polymer, and the solutionmay be either a polymer solution at the end of polymerization (polymerdope) or a solution obtained by appropriate treatment such as dilution,concentration, filtration and washing of the polymer solution. Anorganic solvent is effective if it is the solvent, which can dissolve apolymer and separate from water. Further, the amount of used organicsolvent and water can be appropriately selected in a range of which anorganic solvent layer can separate from an aqueous layer.

As a preferable condition, a polymer solution obtained in thepolymerization step (A) is subjected to extraction (wash) by adding anorganic solvent having a density of 0.95 or less (particularly anorganic solvent having a solubility parameter (SP value) of 20 MPa^(1/2)or less) and water. Further, it is also preferable that a glycol orester solvent solution of a polymer formed by polymerization issubjected to extraction (wash) by adding an organic solvent having adensity of 0.95 or less and a solubility parameter (SP value) of 20MPa^(1/2) or less and water. As density of organic solvent, a value in20° C. to 25° C. can be employed. A SP value of organic solvent can becalculated by, for example, a method represented in “Polymer Handbook”fourth edition, VII page 675 to VII page 711 (particularly, the equation(B3) and the equation (B8) in page 676). Further, as SP value of organicsolvent, the values in the table 1 (VII page 683) and the table 7 totable 8 (VII page 688 to VII page 711) of the said literature can beemployed.

A glycol or ester solvent solution of a polymer formed by polymerizationmay be either a polymer solution at the end of polymerization (polymerdope) or a solution obtained by treating the polymer solution withappropriate treatment such as dilution, concentration, filtration andwashing. As a glycol solvent and an ester solvent, there may bementioned solvents described above.

A density of glycols solvent such as propylene glycol monomethyl etheracetate and esters solvent such as ethyl lactate is close to that ofwater (close to 1), so that it is difficult to separate them from water.However by adding an organic solvent having a density of 0.95 or lessand a SP value of 20 MPa^(1/2) or less (for example, 13 to 20 MPa^(1/2))into the glycol or ester solvent, it becomes extremely easy to separatean organic layer from water. When a density of an added organic solventis over 0.95, a difference of density toward water is less, thereby agood performance of separation is difficult to obtain. Further, when aSP value of an added organic solvent is over 20 MPa^(1/2), solubility inwater is increased, thereby a good performance of separation is alsodifficult to obtain. A density of added organic solvent is preferablyfrom 0.6 to 0.95, more preferably from 0.7 to 0.85 (particularly, from0.7 to 0.82). A SP value of added organic solvent is preferably from 16to 19 MPa^(1/2), more preferably from 16.5 to 18.5 MPa^(1/2)(particularly, from 16.5 to 18 MPa^(1/2)).

As typical examples of an organic solvent having a density of 0.95 orless and a SP value of 20 MPa^(1/2) or less, there may be mentioned, forexample, aliphatic hydrocarbons such as hexane (density 0.659; SP value14.9), octane (density 0.703; SP value 15.6) and dodecane (density0.749; SP value 16.2); alicyclic hydrocarbons such as cyclohexane(density 0.779; SP value 16.8); aromatic hydrocarbons such asethylbenzene (density 0.862; SP value 18.0), p-xylene (density 0.857; SPvalue 18.0), toluene (density 0.867; SP value 18.2), and benzene(density 0.874; SP value 18.8); ethers such as diisopropyl ether(density 0.726; SP value 14.1); ketones such as diisobutyl ketone(density 0.806; SP value 16.0), methyl isobutyl ketone (density 0.796;SP value 17.2), methyl propyl ketone (density 0.809; SP value 17.8),methyl isopropyl ketone (density 0.803; SP value 17.4), methyl ethylketone (density 0.805; SP value 19.0) and methyl amyl ketone (density0.815; SP value 17.6); esters such as isopropyl acetate (density 0.872;SP value 17.2), butyl acetate (density 0.881; SP value 17.4) and propylacetate (density 0.889; SP value 18.0). The density in the aboveparentheses is a value at 20° C. (provided that it is a value at 25° C.for benzene, p-xylene, ethylbenzene and methyl isobutyl ketone) and aunit of SP value is MPa^(1/2).

In these solvents, ketones such as diisobutyl ketone, methyl isobutylketone, methyl propyl ketone, methyl isopropyl ketone and methyl amylketone.

The amount of used organic solvent having a density of 0.95 or less anda SP value of 20 MPa^(1/2) or less can be appropriately selected whileconsidering an efficiency of extraction, an easiness of operation and soon, and is usually from 10 to 300 parts by weight and preferably fromabout 20 to 200 parts by weight relative to 100 parts by weight of aglycol or ester solvent solution of a polymer. Further, the amount ofadded water can be appropriately selected by considering an efficiencyof extraction, an easiness of operation and so on, and is usually from 5to 300 parts by weight and preferably from about 10 to 200 parts byweight relative to 100 parts by weight of a sum of glycol or estersolvent solution of a polymer with the above organic solvent.

An extraction (washing) procedure can be performed by common method andmay be carried out by batch process, semi-batch process or continuousprocess. An extraction procedure may be repeated plural times (forexample, from about 2 to 10 times). An extraction temperature can beselected by considering an easiness of operation, solubility and others,and is, for example, from 0° C. to 100° C. and preferably from about 25°C. to 50° C.

An obtained organic solvent layer may be treated in the filtration stepto remove impurities. A pore size of filtration material used in thefiltration step is, for example, from 1 μm or less, preferably from 0.5μm or less, and more preferably from 0.3 μm or less.

[Precipitation Purification Step (C)]

In the precipitation purification step (C), a polymer formed bypolymerization is precipitated or re-precipitated. By the precipitationpurification step, a raw material a monomer and an oligomer can beeffectively removed. A solution treated in the precipitationpurification step may be a solution containing a polymer formed bypolymerization and may be either a polymerization solution (polymerdope) at the end of polymerization or a solution obtained by suitabletreatment such as dilution, concentration, filtration, washing andextraction of the polymerization solution. A preferable solution is anorganic solvent layer obtained in the said extraction step (B), asolution obtained by filtrating the layer and so on.

A solvent used in a precipitation or re-precipitation (precipitationsolvent) may be a poor solvent for a polymer and can be used byappropriately selecting from, for example, hydrocarbons such as analiphatic hydrocarbon (pentane, hexane, heptane, octane and others),alicyclic hydrocarbons (cyclohexane, methylcyclohexane and others),aromatic hydrocarbons (benzene, toluene, xylene and others); halogenatedhydrocarbons such as halogenated aliphatic hydrocarbons (methylenechloride, chloroform, carbon tetrachloride and others) and halogenatedaromatic hydrocarbons (chlorobenzene, dichlorobenzene and others); nitrocompounds such as nitromethane and nitroethane; nitriles such asacetonitrile and benzonitrile; ethers such as chain ethers (diethylether, diisopropyl ether, dimethoxyethane and others) and cyclic ethers(tetrahydrofuran, dioxane and others); ketones such as acetone, methylethyl ketone, methyl isobutyl ketone and diisobutyl ketone; esters suchas ethyl acetate and butyl acetate; carbonates such asdimethylcarbonate, diethylcarbonate, ethylenecarbonate andpropylenecarbonate; alcohols such as methanol, ethanol, propanol,isopropylalcohol and butanol; carboxylic acids such as acetic acid;water; a mixed solvent comprising these solvents; and so on.

In these solvents, as a precipitation solvent, a mixed solventcontaining at least a hydrocarbon (particularly, aliphatic hydrocarbonssuch as hexane and heptane) is preferable. In the mixed solventcontaining at least a hydrocarbon, a mixing ratio of a hydrocarbon toother solvent (for example, esters such as ethyl acetate and others) is,for example, a hydrocarbon/other solvent=10/90 to 99/1 (volume ratio at25° C., the following is the same), preferably 30/70 to 98/2, and morepreferably about 50/50 to 97/3.

A preferable procedure of this step is that a solution containing apolymer formed by polymerization and a glycol or ester solvent is addedinto a solvent containing at least a hydrocarbon to precipitate orre-precipitate the polymer. As the solution containing a polymer formedby polymerization and a glycol or ester solvent, there may be mentionedan organic solvent layer containing a glycol or ester solvent obtainedin the said extraction step (B), a solution obtained by filtrationtreatment of the layer or others.

[Repulping Step (D)]

In the repulping step (D), a polymer formed by polymerization isrepulped with a solvent. By performing this step, a remained monomer andlow-molecular weight oligomer sticking on a polymer can be effectivelyremoved. Further, probably because of removing a high-boiling-pointsolvent having an affinity to a polymer, hardening of the surface ofpolymer particle, fusion of polymer particles each other and so on canbe prevented in the following steps such as the drying step. Thereby asolubility of polymer in a resist solvent is extremely improved andpreparation of photoresist resin composition comes to be carried outeasily and efficiently.

A material treated in a repulping procedure is the saidprecipitating-purified polymer (for example, a polymer from which asolvent is removed by decantation, a filtration or others after aprecipitation purification) and so on.

As a solvent used in a repulping treatment (repulping solvent), a poorsolvent for the polymer used in a precipitation or re-precipitation ispreferable. Particularly, a hydrocarbon solvent is more preferable. As ahydrocarbon solvent, there may be mentioned, for example, aliphatichydrocarbons such as pentane, hexane, heptane and octane, alicyclichydrocarbons such as cyclohexane and methylcyclohexane, and aromatichydrocarbons such as benzene, toluene and xylene. Two sorts or more ofthese solvents may be used by mixture. In these solvents, an aliphatichydrocarbon, particularly hexane, heptane or a mixed solvent containinghexane or heptane is preferable.

An amount of used repulping solvent is, for example, 1 to 200 times byweight, preferably 5 to 100 times by weight, and more preferably about10 to 50 times by weight, relative to a polymer. A temperatureperforming a repulping treatment, being different according to the sortsof used solvent or others, is usually 0° C. to 100° C. and preferablyabout 10° C. to 60° C. A repulping treatment is performed in a suitablevessel. A repulping treatment may be performed plural times. A treatedliquid (repulping liquid) is removed by decantation and so on.

[Rinsing Step (E)]

In the rinsing step (E), a polymer formed by polymerization is rinsedwith a solvent. By performing this step, a remained monomer andlow-molecular weight oligomer sticking to a polymer can be effectivelyremoved, in the same way as the said repulping step. Further, probablybecause of removing a high-boiling-point solvent having an affinity to apolymer or not, hardening of a surface of polymer, fusing of polymerparticles each other and so on can be prevented in the following dryingstep. Thereby a solubility of polymer in a resist solvent is extremelyimproved and a preparation of photoresist resin composition comes to becarried out easily and efficiently. Furthermore, by using water as arinse solvent, a metal element sticking on a surface of polymer can beefficiently removed. Thereby, a deterioration of resist performancecaused by a metal element can be prevented.

A material treated in the rinsing treatment is theprecipitating-purified polymer (for example, a polymer obtained byremoving a solvent by methods such as decantation after precipitationpurification) or a polymer treated in the repulping treatment (forexample, polymer obtained by removing solvent by decantation afterprecipitation purification) or others.

As a solvent used in a rinse treatment (rinse solvent), a poor solventfor a polymer used in a precipitation or re-precipitation is preferable.Particularly, a hydrocarbon solvent is more preferable. As ahydrocarbon, there may be mentioned, for example, aliphatic hydrocarbonssuch as pentane, hexane, heptane, octane and others, alicyclichydrocarbons such as cyclohexane and methylcyclohexane, and aromatichydrocarbons such as benzene, toluene and xylene. Two sorts or more ofthese solvents may be used by mixture. In these solvents, an aliphatichydrocarbon, particularly hexane or heptane, or a mixed solventcontaining hexane or heptane is preferable. Further, in order to removea metal element from a polymer, water and particularly water having Nacontent of 5 ppb by weight or less (preferably 3 ppb by weight or lessand more preferably 1.5 ppb by weight or less), for example super-purewater, is preferable as a rinse solvent.

An amount of used rinse solvent is, for example, 1 to 100 times byweight and preferably about 2 to 20 times by weight relative to apolymer. A temperature performing a rinse treatment, being differentaccording to the sorts of used solvent or others, is usually 0° C. to100° C. and preferably about 10° C. to 60° C. A rinse treatment isperformed in a suitable vessel. A rinse treatment may be performedplural times. Particularly, performing a rinse treatment using ahydrocarbon solvent and a rinse treatment using water in combination ispreferable. A treated liquid (rinse liquid) is removed by decantation,filtration and so on.

[Drying Step (F)]

In the drying step (F), the polymer produced by polymerization issubjected to precipitation purification, and if necessary, is treated bythe repulping treatment and/or the rinse treatment, and subsequently theresulting polymer is dried. A drying temperature of polymer is, forexample, 20° C. to 120° C. and preferably about 40° C. to 100° C. Thedrying is performed under a reduced pressure, for example 200 mmHg (26.6kPa) or less and preferably 100 mmHg (13.3 kPa) or less.

[Redissolving Step (G)]

In the redissolving step (G), the polymer produced by polymerization issubjected to precipitation purification, and if necessary, is treated bythe repulping treatment, the rinse treatment, and/or the dryingtreatment, and subsequently the resulting polymer is allowed to resolvein organic solvent (resist solvent) to prepare the polymer solution.This polymer solution can be applied to a photoresist polymer solution(a concentration of polymer of about 10 to 40% by weight). Such organicsolvents include, but are not limited to, the solvents exemplified asthe polymerization solvents such as glycols solvent, esters solvent,ketones solvent, and a mixed solvent thereof. Among these solvents,propylene glycol monomethyl ether, propylene glycol monomethyl etheracetate, ethyl lactate, methyl isobutyl ketone, methyl amyl ketone and amixed solvent thereof are preferable and particularly solventscontaining at least propylene glycol monomethyl ether acetate such as asingle solvent of propylene glycol monomethyl ether acetate, a mixedsolvent of propylene glycol monomethyl ether acetate with propyleneglycol monomethyl ether and a mixed solvent of propylene glycolmonomethyl ether acetate with ethyl lactate can be appropriately used.

[Evaporating Step (H)]

In the evaporating step (H), the polymer solution obtained in the saidredissolving step (G) is concentrated and a low-boiling-point solventcontained in the polymer solution (for example, solvents used as thepolymerization solvent, the extraction solvent, the precipitatingsolvent, the repulping solvent and the rinse solvent) is removed byevaporating to prepare a photoresist polymer solution. The evaporatingstep (H) is useful in case of containing a low-boiling-point solvent inthe polymer solution obtained in the redissolving step (G), for example,in case of the process comprising the redissolving step (G) without thedrying step (F). In case of including the evaporating step (H), equal toor more than the required amount of organic solvent (resist solvent) inpreparation of photoresist polymer solution is added and the resultingsolution is concentrated to a desired polymer concentration (forexample, about 10 to 40% by weight) in the redissolving step (G). Theconcentration can be performed at atmospheric pressure or under areduced pressure.

Further, the photoresist polymer solution is added a photo-acidgenerator, and if necessary, various additives and is applied to amanufacture of semiconductor.

[Passing Liquid Step (I)]

In the passing liquid step (I), a polymer solution which contains apolymer (hereinafter, it may be described as “polymer P”) having arepeated unit corresponding to at least one monomer selected from theabove monomers, (a), (b) and (c), and of which a metal content is 1000ppb by weight or less relative to the above polymer P is subjected topassing through a filter constituted by a porous polyolefin membranehaving a cation-exchange group.

The polymer P may contain one of a repeated unit corresponding to amonomer (a) [for example, a repeated unit corresponding to a(meth)acrylic acid ester monomer represented by the above formula (1a),(1b) or (1c) (such as a repeated unit formed by polymerization of anacryl moiety) and others], a repeated unit corresponding to the monomer(b) [for example, a repeated unit corresponding to a (meth)acrylic acidester monomer represented by the above formula (2a) or (2b) (such as arepeated unit formed by polymerization of an acryl moiety), and others]and a repeated unit corresponding to the monomer (c) [for example, arepeated unit corresponding to a (meth)acrylic acid ester monomerrepresented by the above formula (3a) (such as a repeated unit formed bypolymerization of an acryl moiety) and others]. Further, the polymer Pcontaining two or more, particularly three among the above threerepeated units are preferable. In addition, the polymer P may, ifnecessary, contain other repeated unit.

The said polymer P can be synthesized by the process of the above step(A). In detail, at least one monomer (an acryl monomer, an olefinmonomer and others) selected from a monomer having a lactone skeleton, amonomer having a group which becomes soluble in alkali by eliminationwith an acid and a monomer containing a alicyclic skeleton having ahydroxyl group, and if necessary, other monomers are polymerized andthereby the polymer is synthesized. Polymerization can be performed byconventional techniques such as solution polymerization and meltpolymerization. A monomer having a low metal content, for example, amonomer having a metal content of 100 ppb by weight or less ispreferably employed as a monomer.

A solvent for a solution containing the polymer P is not limitedparticularly. There may be mentioned, for example, esters such as ethylacetate, butyl acetate, propylene glycol monomethyl ether acetate, ethyllactate and ethyl benzoate; ketones such as acetone, ethyl methylketone, diethyl ketone, isobutyl methyl ketone and t-butyl methylketone; chain or cyclic ethers such as diethyl ether, diisopropyl ether,t-butyl methyl ether, dibutyl ether, dimethoxy ethane, propylene glycolmonomethyl ether, anisole, dioxane and tetrahydrofuran; alcohols such asmethanol, ethanol, isopropyl alcohol and butanol; nitriles such asacetonitrile, propionitrile and benzonitrile; aromatic hydrocarbons suchas benzene, toluene, xylene and ethylbenzene; aliphatic hydrocarbonssuch as hexane, heptane and octane; alicyclic hydrocarbons such ascyclohexane; halogenated hydrocarbons such as dichloromethane,1,2-dichloroethane and chlorobenzene; amides such asN,N-dimethylformamide; carbon disulfide; water; a mixed solvent thereof;and others. Among these solvents, esters, ketones, mixed solventscontaining these solvents and others are preferable. The said solventmay be a polymerization solvent and also may be a solvent replaced froma polymerization solvent.

A cation-exchange group constituting the porous polyolefin membraneincludes a strong-acidity cation-exchange group such as a sulfonic acidgroup, a weak-acidity cation-exchange group such as a carboxyl group andothers. As a polyolefin constituting the polyolefin membrane, forexample, polyethylenes such as high-density polyethylene, polypropyleneand others are represented.

As a filter constituted by the porous polyolefin membrane having acation-exchange group, a hydrophilic one is preferable and, for example,“IONCLEAN”, trade name of a product available from Nihon Pole Ltd. andothers are appropriately used.

In the step (I), when a solution containing the said polymer P(photoresist polymeric compound) is passed through a filter constitutedby a porous polyolefin membrane having a cation-exchange group to removea metal ion, and thereby a hydrogen ion (acid) is stoichiometricallygenerated. Because this hydrogen ion causes an acid-eliminating group ofthe polymer P to eliminate to thereby deteriorate a resist performance,the hydrogen ion is preferably as few as possible. Therefore, a metalcontent of solution containing the polymer P provided to a filterconstituted by a porous polyolefin membrane having a cation-exchangegroup is 1000 ppb by weight or less (for example, 10 to 1000 ppb byweight), preferably 800 ppb by weight or less (for example, 10 to 800ppb by weight), and more preferably 500 ppb by weight or less (forexample, 10 to 500 ppb by weight) relative to the polymer P. In casethat the said metal content exceeds 1000 ppb by weight, a hydrogen ionconcentration of the solution passed through a filter increases and tothereby deteriorate a resist performance.

Flow rate in passing a solution containing the polymer P through filteris different according to the sorts of material for polyolefin membrane,the sorts of solution (solvent) or others and can be appropriatelyselected in a range of not deteriorating a metal-removing efficiency(for example, from about 100 ml/min to 100 L/min). A temperature inpassing through filter is commonly from 0° C. to 80° C. and preferablyfrom about 10° C. to 50° C. When the temperature is too high, there issome fear of deterioration of a filter, decomposition of a solvent orothers. When the temperature is too low, a viscosity of a solutionbecomes high and thereby passing is likely to be difficult.

By passing a solution containing the polymer P through the said filter,metal ions such as sodium ion and iron ion contained in the solution areefficiently removed and a polymer solution having a metal content on thebasis of polymer of, for example, 200 ppb by weight or less andpreferably 100 ppb by weight or less can be obtained. Therefore, in caseof using the polymer P as a resin component of photoresist resincomposition, it comes not to make any bad influence on electricalcharacteristics of semiconductor and so on.

[Filtration Step (J)]

In the present invention, the filtration step (J) in which a solutioncontaining the polymer P is filtrated to remove insolubles may beperformed before the above step (I). By performing the filtration step(J), a blockage in the step (I) can be prevented and various troublescaused by a contamination of foreign matter can be prevented in case offorming a pattern using a photoresist resin composition as well as.

A filter material used in the filtration step (J) isn't particularlylimited and commonly a membrane filter and others are employed. A poresize of a filter material is usually from 0.01 to 10 μm, preferably from0.02 to 1 μm, and more preferably from about 0.05 to about 0.5 μm.

[Water Washing Treatment Step (K)]

In the present invention, the water washing treatment step (K) in whicha metal content of the solution is deceased by washing the solutioncontaining the polymer P with water may be performed before the step(I). Performing water washing treatment step (K) before the step (I)brings a big advantage. Such advantage not only includes that anwater-soluble metal compound can be efficiently removed and to therebyreduce a load on the step (I), but also includes that the amount ofhydrogen ion generated accompanied with removal of metal ion in the step(I) can be reduced and to thereby prevent from the deterioration of aresist performance. Particularly, when a metal content of solutioncontaining the polymer P exceeds 1000 ppb by weight, it is possible toprovide the step (I) with a solution having a metal content of thesolution to be reduced to 1000 ppb by weight or less in the waterwashing treatment step (K).

As water used in the water washing treatment step (K), water of which ametal content is few, and for example, super-pure water of which a metalcontent is 1 ppb by weight or less, is preferable. An amount of wateris, for example, from 10 to 1000 parts by weight and preferably fromabout 30 to about 300 parts by weight relative to 100 parts by weight oftreated liquid. A temperature in the water washing treatment is, forexample, from about 10° C. to about 50° C. Further, the water washingtreatment step alone can reduce a metal content in a polymer solution toa desired level without the step (I), however, in this case large amountof waste water containing metal is generated and the treatment thereofneeds some running cost, which is a disadvantage.

When the said filtration step (J) and the water washing treatment step(K) are performed, an order of the both steps isn't restricted andhowever the filtration step (J) is usually performed previously.

In the present invention, if necessary, a step of performing otheradsorption treatment of a solution containing the polymer P to may becarried out except for the above steps. Such other adsorption treatmentincludes, for example, an active carbon treatment, a chelate resintreatment, a chelate fiber treatment, a zeta potential membranetreatment, and so on. Further, each of the above steps (B), (C), (D),(E), (F), (G) and (H) can be performed before or after the said step(I).

A solution containing the polymer P (photoresist polymeric compound)performed by the above steps is used for preparation of photoresistresin composition as intact or after isolation of the polymer byprecipitation, a re-precipitation or other treatments.

A solvent (precipitation solvent) used for precipitation orre-precipitation may be a poor solvent toward a polymer and can be usedby appropriately selecting from, for example, hydrocarbons such asaliphatic hydrocarbons (e.g., pentane, hexane, heptane, octane and soon), alicyclic hydrocarbons (e.g., cyclohexane, methylcyclohexane and soon), aromatic hydrocarbons (e.g., benzene, toluene, xylene and so on);halogenated hydrocarbons such as halogenated aliphatic hydrocarbons(e.g., methylene chloride, chloroform, carbon tetrachloride and so on)and halogenated aromatic hydrocarbons (e.g., chlorobenzene,dichlorobenzene and so on); nitro compounds such as nitromethane andnitroethane; nitriles such as acetonitrile and benzonitrile; ethers suchas chain ethers (e.g., diethyl ether, diisopropyl ether, dimethoxyethane and so on) and cyclic ethers (e.g., tetrahydrofuran, dioxane andso on); ketones such as acetone, methyl ethyl ketone, methyl isobutylketone and diisobutyl ketone; esters such as ethyl acetate and butylacetate; carbonates such as dimethyl carbonate, diethyl carbonate,ethylene carbonate and propylene carbonate; alcohols such as methanol,ethanol, propanol, isopropyl alcohol and butanol; carboxylic acids suchas acetic acid; water; a mixed solvent containing these solvents; andothers. Among these solvents, as a precipitation solvent a mixed solventcontaining at least hydrocarbons (particularly, aliphatic hydrocarbonssuch as hexane and heptane) are preferable. In the mixed solventcontaining at least hydrocarbons, a mixing ratio of hydrocarbons withanother solvent (e.g., esters such as ethyl acetate) is, for example,hydrocarbons/another solvent=10/90 to 99/1 (ratio by volume at 25° C.,which has the same meaning hereinafter), preferably from 30/70 to 98/2,and more preferably from about 50/50 to about 97/3. As a precipitationsolvent, a solvent having a low metal content, for example, metalcontent of 50 ppb by weight or less, is preferably used.

Industrial Applicability

The process for producing photoresist polymeric compounds of the presentinvention can efficiently provide a photoresist polymeric compoundhaving an impurity such as metal content of extremely few. Further,particularly in case of performing the said steps (A) and (B) in theprocess, the process can efficiently provide a photoresist polymericcompound dissolving in a photoresist solvent easily and certainly.

In addition, particularly in case of including the said step (I), whenthe photoresist polymeric compound is used as a resin component ofphotoresist resin composition, a desired resist performance can beobtained because a metal component having a bad influence uponelectrical characteristics can be efficiently removed.

EXAMPLES

Hereinafter, the present invention will be described in further detailwith reference to several examples, which are not intended to limit thescope of the invention. Additionally, the numerals in the right bottomof parentheses written in the formulae of Examples 11, 13, 14 and 15represents % by mole of monomer units (repeated units). In Examples 11to 15 and Comparative Examples 4 to 6, monomers having metal content of100 ppb by weight or less were used. In regard to propylene glycolmonomethyl ether acetate (PGMEA) and methyl isobutyl ketone (MIBK),commercially available agents were distilled by a glass-madedistillation equipment to become metal content of 50 ppb by weight orless before and the results are used in Example 11. In Examples exceptfor Example 11, commercially available agents were used as intact. InExamples 11 to 15 and Comparative Examples 4 to 6, solvents (ethylacetate, hexane) used in the precipitation procedure and the repulpingprocedure is the solvent distilled by a glass-made distillationequipment to become metal content of 50 ppb by weight or less beforeuse, and in regard to water, super-pure water (provided by allowing purewater to ion-exchange treatment and then treating by membrane to becomemetal content of 1 ppb by weight or less) was used. The metal contentwas determined by an induction coupling plasma mass spectroscopy(ICP-MS) and represented by value (ppb) relative to the amount ofpolymer obtained finally. The term “ppb” means “ppb by weight”.

Example 1

Production of photoresist polymeric compound with following structure

In an separable flask equipped with a stirrer, a thermometer, arefluxing condenser, a dropping funnel and a nitrogen gas introducingtube, 33 g of propylene glycol monomethyl ether acetate (PGMEA) wascharged and after the solution was raised in temperature up to 75° C., amixed solution containing 5 g of 1-hydroxy-3-methacryloyloxyadamantane(HMA), 5 g of 5-methacryloyloxy-2,6-norbornane carbolactone (MNBL), 5 gof 2-methacryloyloxy-2-methyladamantane (2-MMA), 0.93 g ofdimethyl-2,2′-azobis(2-methylpropionate) (initiator; “V-601” produced byWako Pure Chemical Industries, Ltd.) and 41 g of propylene glycolmonomethyl ether acetate (PGMEA) was added by dropping over 6 hours.After dropping, the resulting mixture was aged for 2 hours. 54 g ofmethyl isobutyl ketone (MIBK) (35° C.) was added to the obtainedreaction mixture (polymer dope) (35° C.) and to the obtained polymersolution, water of the same weight as the polymer solution was added.The resulting mixture was stirred at 35° C. for 30 minutes andthereafter was kept standing for 30 minutes to separate the mixture.After removing the lower layer (aqueous layer), new water of the sameamount as the upper layer (organic layer) was added to the upper layer,was stirred again at 35° C. for 30 minutes and was kept standing for 30minutes, and the lower layer (aqueous layer) was removed. After passingthe upper layer (organic layer) (35° C.) through a filter havingmicro-hole diameter of 0.5 μm and a filter having that of 0.1 μm, theresulting mixture was added dropwise to the mixture (35° C.) of 656 g ofheptane and 219 g of ethyl acetate, and after the completion of addingdropwise, the resulting solution was stirred for 60 minutes and was keptstanding for 90 minutes. The precipitation purification was performed bythese procedures.

After removing 640 g of supernatant, 640 g of heptane was added to theresidue and the repulping procedure was performed at 35° C. Therepulping procedure was performed by adding heptane, stirring for 30minutes, keeping standing for 90 minutes and removing the supernatant.The repulping procedure was performed twice in all. After removing thesupernatant, the residue was transfer to a centrifuge to remove liquidunder 600 G of centrifugal force and to thereby yield a wet polymer. 65g of heptane was added to the wet polymer and a rinse procedure wasperformed under 600 G of centrifugal force to remove rinsing liquid.Then 100 g of super-pure water (Na content of 0.9 ppb by weight) wasadded and was rinsed under 600 G of centrifugal force to remove rinsingliquid.

The resulting wet polymer was taken out and was added to a tray dryer todry under 20 mmHg (2.66 kPa) at 70° C. for 30 hours, and 10.5 g ofphotoresist polymer (ArF resist resin) was obtained. The photoresistpolymer was dissolved in 31.5 g of PGMEA to prepare the photoresistpolymer solution.

The obtained photoresist polymer had a weight average molecular weightof 8250, a molecular weight distribution of 1.74, and the metal contentson the basis of the polymer weight were Na of 95 ppb by weight, Mg of 40ppb by weight, K of 40 ppb by weight, Ca of 45 ppb by weight, Zn of 48ppb by weight, Fe of 38 ppb by weight, Al of 20 ppb by weight, Cr of 20ppb by weight, Mn of 35 ppb by weight, Ni of 20 ppb by weight, and Cu of20 ppb by weight and the polymer contained 0.05% by weight of MNBL,0.05% by weight of HMA, and 0.08% by weight of 2-MMA as remainedmonomers, 2.5% by weight of remained solvent and 0.5% by weight ofmoisture. In addition, the solubility of photoresist polymer in PGMEAwas good.

Example 2

In the same way as in Example 1, the reaction (polymerization), thewater washing (extraction), the filtration and the precipitationpurification were performed. Then, after removing 640 g of thesupernatant made in the precipitation purification, the residue wastransferred to a centrifuge to remove liquid under 600 G of centrifugalforce and the wet polymer was obtained. 65 g of heptane was added to thewet polymer and the rinsing procedure was performed under 600 G ofcentrifugal force to remove rinsing liquid. Then 100 g of super-purewater (Na content; 0.9 ppb by weight) was added and the residue wasrinsed under 600 G of centrifugal force to remove rinsing liquid.

The obtained wet polymer (42 g) was dissolved in 63 g of methyl amylketone. By concentrating the resulting solution (from atmosphericpressure to 2.66 kPa; from room temperature to 75° C.), 42 g of 25% byweight of photoresist polymer solution was obtained.

The obtained photoresist polymer had a weight average molecular weightof 8200, a molecular weight distribution of 1.75, and the metal contentson the basis of the polymer weight were Na of 94 ppb by weight, Mg of 30ppb by weight, K of 35 ppb by weight, Ca of 40 ppb by weight, Zn of 50ppb by weight, Fe of 42 ppb by weight, Al of 20 ppb by weight, Cr of 20ppb by weight, Mn of 5 ppb by weight, Ni of 5 ppb by weight, and Cu of10 ppb by weight and the polymer contained 0.09% by weight of MNBL,0.09% by weight of HMA, and 0.11% by weight of 2-MMA as remainedmonomers.

Comparative Example 1

A photoresist polymer solution was obtained in the same manner as inExample 2 except that the water washing (extracting) procedure wasn'tperformed. In the obtained photoresist polymer, the metal contents onthe basis of the polymer weight were Na of 550 ppb by weight, Mg of 80ppb by weight, K of 240 ppb by weight, Ca of 300 ppb by weight, Zn of250 ppb by weight, Fe of 300 ppb by weight, Al of 200 ppb by weight, Crof 80 ppb by weight, Mn of 30 ppb by weight, Ni of 30 ppb by weight, andCu of 40 ppb by weight.

Example 3

A reaction (polymerization) was performed in the same manner as inExample 1. The obtained reaction liquid (polymer dope) (35° C.) waspassed through a filter having micro-hole diameter of 0.5 μm and afilter having that of 0.1 μm and then was added drop by drop into themixture (35° C.) containing 656 g of heptane and 219 g of ethyl acetate,and after completion of adding dropwise, the resulting solution wasstirred for 60 minutes and was kept standing for 90 minutes. Theprecipitation purification was performed by these procedures. Afterremoving the supernatant made in the precipitation purification, theresidue was transferred to a centrifuge to remove liquid under 600 G ofcentrifugal force and the wet polymer was obtained. The wet polymer wasadded into 63 g of methyl amyl ketone (MAK) and dissolved at 60° C. Inthe resulting polymer solution, the same weight of water was added. Theresulting mixture was stirred at 35° C. for 30 minutes and thereafterwas kept standing for 30 minutes to separate. After removing the lowerlayer (aqueous layer), newly water of the same amount as the upper layer(organic layer) was added and the resulting mixture was again stirred at35° C. for 30 minutes and was kept standing for 30 minutes and the lowerlayer (aqueous layer) was removed. The upper layer (organic layer) wasconcentrated (from atmospheric pressure to 2.66 kPa; from roomtemperature to 75° C.) and 42 g of 25% by weight of photoresist polymersolution was obtained.

The obtained photoresist polymer had a weight average molecular weightof 8280, a molecular weight distribution of 1.76, and the metal contentson the basis of the polymer weight were Na of 85 ppb by weight, Mg of 25ppb by weight, K of 30 ppb by weight, Ca of 35 ppb by weight, Zn of 45ppb by weight, Fe of 40 ppb by weight, Al of 15 ppb by weight, Cr of 15ppb by weight, Mn of 5 ppb by weight, Ni of 5 ppb by weight, and Cu of10 ppb by weight and the polymer contained 0.09% by weight of MNBL,0.08% by weight of HMA, and 0.10% by weight of 2-MMA as remainedmonomers.

Example 4

Production of photoresist polymeric compound with following structure

In an separable flask equipped with a stirrer, a thermometer, arefluxing condenser, a dropping funnel and a nitrogen gas introducingtube, 12.0 g of propylene glycol monomethyl ether acetate (PGMEA) wascharged and after raising the temperature to 75° C., the mixed solutioncontaining 3.37 g of 1-acryloyloxy-3-hydroxyadamantane (HAA), 3.60 g of5-acryloyloxy-2,6-norbornane carbolactone (ANBL), 8.03 g of1-(1-acryloyloxy-1-methylethyl)adamantane (IAA), 0.85 g ofdimethyl-2,2′-azobis(2-methylpropionate) (initiator; “V-601” produced byWako Pure Chemical Industries, Ltd.) and 48 g of propylene glycolmonomethyl ether acetate (PGMEA) was added by dropping over 6 hours.After dropping, the resulting mixture was aged for 2 hours. After theobtained reaction mixture (polymer dope) (30° C.) was passed through afilter having 0.5 μm of pore size, 75 g of methyl isobutyl ketone (MIBK)(30° C.) was added to the mixture and water of the same weight as theobtained polymer solution was added to the obtained polymer. Theresulting mixture was stirred at 30° C. for 30 minutes and thereafterwas kept standing for 30 minutes to separate. After removing the lowerlayer (aqueous layer), newly water of the same amount as the upper layerwas added into the upper layer (organic layer) and the resulting mixturewas again stirred at 30° C. for 30 minutes and was kept standing for 30minutes to remove the lower layer (aqueous layer). After passing theupper layer (organic layer) (30° C.) through a filter having 0.1 μm ofpore size, the resulting mixture was added drop by drop into the mixture(30° C.) containing 832 g of heptane and 92 g of ethyl acetate, andafter completion of adding dropwise, the resulting solution was stirredfor 60 minutes. The precipitation purification was performed by theseprocedures.

This residue was transferred to a centrifuge to remove liquid under 600G of centrifugal force and the wet polymer was obtained. 116 g ofheptane was added to the wet polymer and a rinsing procedure wasperformed under 600 G of centrifugal force to remove rinsing liquid.Then 110 g of super-pure water (Na content; 0.1 ppb by weight) was addedand the residue was rinsed under 600 G of centrifugal force to removerinsing liquid.

The resulting wet polymer was taken out and was transferred to a traydryer to dry under 20 mmHg (2.66 kPa) at 45° C. for 65 hours, and 12 gof photoresist polymer (ArF resist resin) was obtained. The photoresistpolymer was dissolved in 36 g of PGMEA to prepare the photoresistpolymer solution.

The obtained photoresist polymer had a weight average molecular weightof 15000, a molecular weight distribution of 2.50, and the Na content onthe basis of the polymer weight was 70 ppb by weight. In addition, thesolubility of photoresist polymer in PGMEA was good.

Example 5

In the same way as in Example 4, the reaction (polymerization), thewater washing (extraction), the filtration, the precipitationpurification and the rinsing procedure were performed. The obtained wetpolymer (24 g) was dissolved in 96 g of PGMEA. The resulting solutionwas concentrated (from atmospheric pressure to 8 kPa; from roomtemperature to 80° C.) and 48 g of 25% by weight of photoresist polymersolution was obtained.

The obtained photoresist polymer had a weight average molecular weightof 14800, a molecular weight distribution of 2.45, and the Na content onthe basis of the polymer weight was 65 ppb by weight. In addition, thesolubility of photoresist polymer in PGMEA was good.

Comparative Example 2

A photoresist polymer solution was obtained in the same manner as inExample 5, except that the water washing (extracting) procedure wasn'tperformed. In the obtained photoresist polymer, the metal contents onthe basis of the polymer weight were Na of 500 ppb by weight, Mg of 70ppb by weight, K of 150 ppb by weight, Ca of 480 ppb by weight, Zn of840 ppb by weight, Fe of 150 ppb by weight, Al of 80 ppb by weight, Crof 70 ppb by weight, Mn of 40 ppb by weight, Ni of 40 ppb by weight, andCu of 40 ppb by weight.

Example 6

Production of photoresist polymeric compound with following structure

In an separable flask equipped with a stirrer, a thermometer, arefluxing condenser, a dropping funnel and a nitrogen gas introducingtube, 23.6 g of propylene glycol monomethyl ether acetate (PGMEA) and10.1 g of propylene glycol monomethyl ether (PGME) were charged andafter raising the temperature to 100° C., the mixed solution containing2.72 g of 1,3-dihydroxy-5-methacryloyloxyadamantane (DHMA), 6.74 g of5-acryloyloxy-2,6-norbornane carbolactone (ANBL), 7.54 g of1-(1-methacryloyloxy-1-methylethyl)adamantane (IAM), 0.15 g ofdimethyl-2,2′-azobis(2-methylpropionate) (initiator; “V-601” produced byWako Pure Chemical Industries, Ltd.) and 43.8 g of propylene glycolmonomethyl ether acetate (PGMEA) and 18.8 g of propylene glycolmonomethyl ether (PGME) were added by dropping over 6 hours. Afterdropping, the resulting mixture was aged for 2 hours. After the obtainedreaction mixture (polymer dope) (35° C.) was passed through a filterhaving 0.5 μm of pore size, 56.7 g of methyl isobutyl ketone (MIBK) (35°C.) was added to the mixture and then water of the half weight of theobtained polymer was added to the obtained polymer solution. Theresulting mixture was stirred at 35° C. for 30 minutes and thereafterwas kept standing for 30 minutes to separate. After removing the lowerlayer (aqueous layer), newly water of the half amount of the upper layer(organic layer) was added into the upper layer and the resulting mixturewas again stirred at 35° C. for 30 minutes and was kept standing for 30minutes and the lower layer (aqueous layer) was removed. After passingthe upper layer (organic layer) (35° C.) through filter having 0.1 μm ofpore size, the resulting mixture was added drop by drop into the mixture(35° C.) containing 913.5 g of heptane and 136.5 g of ethyl acetate, andafter completion of adding dropwise, the resulting solution was stirredfor 30 minutes. The precipitation purification was performed by theseprocedures.

This residue was transferred to a centrifuge to remove liquid under 600G of centrifugal force and the wet polymer was obtained. 210 g ofheptane was added to the wet polymer and a rinsing procedure wasperformed under 600 G of centrifugal force to remove rinsing liquid.Then 210 g of super-pure water (Na content of 0.8 ppb by weight) wasadded and was rinsed under 600 G of centrifugal force to remove rinsingliquid.

The resulting wet polymer was taken out and transferred to a tray dryerto dry under 20 mmHg (2.66 kPa) at 45° C. for 40 hours, and 14 g ofphotoresist polymer (ArF resist resin) was obtained. The photoresistpolymer was dissolved in the mixed solvent containing 29 g of PGMEA and13 g of PGME to prepare the photoresist polymer solution.

The obtained photoresist polymer had a weight average molecular weightof 9700, a molecular weight distribution of 2.14, and the Na content onthe basis of the polymer weight was 50 ppb by weight. In addition, thesolubility of photoresist polymer in the mixed solvent of PGMEA/PGME[=7/3 (weight ratio)] was good.

Example 7

In the same way as in Example 6, the reaction (polymerization), thewater washing (extraction), the filtration, the precipitationpurification and the rinsing procedure were performed. The obtained wetpolymer (42 g) was dissolved in 98 g of the mixed solvent of PGMEA/PGME[=7/3 (ratio by weight)]. The resulting solution was concentrated (fromatmospheric pressure to 8 kPa; from room temperature to 70° C.) and 56 gof 25% by weight of photoresist polymer solution was obtained.

The obtained photoresist polymer had a weight average molecular weightof 9750, a molecular weight distribution of 2.12, and the Na content onthe basis of the polymer weight was 48 ppb by weight.

Comparative Example 3

A photoresist polymer solution was obtained in the same manner as inExample 7, except that the water washing (extracting) procedure wasn'tperformed. In the obtained photoresist polymer, the metal contents onthe basis of the polymer weight were Na of 800 ppb by weight, Mg of 70ppb by weight, K of 140 ppb by weight, Ca of 150 ppb by weight, Zn of190 ppb by weight, Fe of 140 ppb by weight, Al of 90 ppb by weight, Crof 70 ppb by weight, Mn of 30 ppb by weight, Ni of 30 ppb by weight, andCu of 30 ppb by weight.

Example 8

In the same manner as in Example 1 except that 1.16 g of2,2′-azobis[2-methyl-N-(2-hydroxyethyl)propionamide] (initiator;“VA-086” produced by Wako Pure Chemical Industries, Ltd.) instead of0.93 g of dimethyl-2,2′-azobis(2-methylpropionate) (initiator; “V-601”produced by Wako Pure Chemical Industries, Ltd.) as a polymerizationinitiator, 41 g of ethyl lactate instead of 33 g of propylene glycolmonomethyl ether acetate (PGMEA) as the solvent as the solvent firstlycharged to the flask, and 41 g of ethyl lactate instead of 41 g ofpropylene glycol monomethyl ether acetate (PGMEA) as the solvent of themixed solution for dropping were employed, 10.2 g of a photoresistpolymer (ArF resist resin) was obtained. In addition, by employing thepolymer, a photoresist polymer solution was obtained in the same manneras in Example 1.

The obtained photoresist polymer had a weight average molecular weightof 8350, a molecular weight distribution of 1.80, and the metal contentson the basis of the polymer weight were Na of 85 ppb by weight, Mg of 43ppb by weight, K of 30 ppb by weight, Ca of 50 ppb by weight, Zn of 44ppb by weight, Fe of 30 ppb by weight, Al of 15 ppb by weight, Cr of 20ppb by weight, Mn of 30 ppb by weight, Ni of 25 ppb by weight, and Cu of20 ppb by weight, and the polymer contained 0.05% by weight of MNBL,0.05% by weight of HMA, and 0.06% by weight of 2-MMA as remainedmonomers, 2.5% by weight of remained solvent and 0.5% by weight ofwater. In addition, the solubility of photoresist polymer in PGMEA wasgood.

Example 9

In the same manner as in Example 4 except that 1.16 g of2,2′-azobis[2-methyl-N-(2-hydroxyethyl)propionamide] (initiator;“VA-086” produced by Wako Pure Chemical Industries, Ltd.) instead of0.85 g of dimethyl-2,2′-azobis(2-methylpropionate) (initiator; “V-601”produced by Wako Pure Chemical Industries, Ltd.) as a polymerizationinitiator, 12.0 g of ethyl lactate instead of 12.0 g of propylene glycolmonomethyl ether acetate (PGMEA) as the solvent firstly charged to theflask and 48 g of ethyl lactate instead of 48 g of propylene glycolmonomethyl ether acetate (PGMEA) as the solvent of the mixed solutionfor dropping were employed, 11.5 g of a photoresist polymer (ArF resistresin) was obtained. In addition, by employing the polymer, aphotoresist polymer solution was obtained in the same manner as inExample 4.

The obtained photoresist polymer had a weight average molecular weightof 14500, a molecular weight distribution of 2.35, and the metalcontents on the basis of the polymer weight were Na of 60 ppb by weight.In addition, the solubility of photoresist polymer in PGMEA was good.

Example 10

In the same manner as in Example 6 except that 0.19 g of2,2′-azobis[2-methyl-N-(2-hydroxyethyl)propionamido] (initiator;“VA-086” produced by Wako Pure Chemical Industries, Ltd.) instead of0.15 g of dimethyl-2,2′-azobis(2-methylpropionate) (initiator; “V-601”produced by Wako Pure Chemical Industries, Ltd.) as a polymerizationinitiator, 33.7 g of ethyl lactate instead of 23.6 g of propylene glycolmonomethyl ether acetate (PGMEA) and 10.1 g of propylene glycolmonomethyl ether (PGME) as the solvent firstly charged to the flask, and62.6 g of ethyl lactate instead of 43.8 g of propylene glycol monomethylether acetate (PGMEA) and 18.8 g of propylene glycol monomethyl ether(PGME) as the solvent of the mixed solution for dropping, 12.8 g of aphotoresist polymer (ArF resist resin) was obtained. In addition, byemploying the polymer, a photoresist polymer solution was obtained inthe same manner as in Example 6.

The obtained photoresist polymer had a weight average molecular weightof 10500, a molecular weight distribution of 2.20, and the Na content onthe basis of the polymer weight was 55 ppb by weight. In addition, thesolubility of photoresist polymer in the mixed solvent of PGMEA/PGME[=7/3 (ratio by weight)] was good.

Example 11

Production of photoresist polymeric compound with following structure

In a reactor equipped with a stirrer, a thermometer, a refluxingcondenser, a dropping tube and a nitrogen gas introducing tube, 70 g ofpropylene glycol monomethyl ether acetate (PGMEA) was charged and afterraising the temperature to 100° C., the mixed solution containing 73.0 gof 5-methacryloyloxy-2,6-norbornane carbolactone (MNBL) (metal contentof 100 ppb or less), 77.0 g of 2-methacryloyloxy-2-methyladamantane(2-MMA), 1.8 g of azobisisobutyronitrile and 530 g of PGMEA was added bydropping over 6 hours. After dropping, the resulting mixture was agedfor 2 hours and the polymer solution containing 20% by weight of thepolymeric compound represented by the above formula was obtained. Thepolymer solution was passed through a membrane filter having 0.5 pm ofpore size and then 750 g of methyl isobutyl ketone (MIBK) was added. Atthat time, the metal content in the polymer solution was 450 ppb.

The polymer solution was passed through “IONCLEAN” (trade name)(produced by Nihon Pole Ltd. the quality of material: the super highmolecular weight polyethylene of chemical modified type, the filtrationarea: 0.11 m²) constituted by a porous polyolefin membrane having acation-exchange group at 100 g/min of flow rate at room temperature.

The obtained solution was dropped into a mixed solvent of 6750 g ofhexane and 2250 g of ethyl acetate and the resulting precipitate wasrepulped with 6500 g of hexane. The supernatant was removed, the residuewas transferred to a centrifuge and the wet polymer was obtained byremoving liquid. The obtained polymer was taken out, was dried under 20mmHg (2.66 kPa) at 70° C. for 30 hours and 108 g of the product polymerwas obtained. The metal content in the product polymer was 50 ppb.

Comparative Example 4

A polymer solution was obtained in the same manner as in Example 11except that a commercially available product of PGMEA was used asintact. The polymer solution was passed through a membrane filter having0.5 μm of pore size and then 750 g of commercially available methylisobutyl ketone (MIBK) was added. At that time, the metal content in thepolymer solution was 1200 ppb.

The polymer solution was passed through “IONCLEAN” (trade name)(produced by Nippon pole Co. Ltd., the quality of material: the superhigh molecular weight polyethylene of chemical modified type, thefiltration area: 0.11 m²) constituted by a porous polyolefin membranehaving a cation-exchange group at 100 g/min of flow rate at roomtemperature.

The obtained solution was dropped into a mixed solvent of 6750 g ofhexane and 2250 g of ethyl acetate and the resulting precipitate wasrepulped with 6500 g of hexane. The supernatant was removed, the residuewas transferred to a centrifuge and the wet polymer was obtained byremoving liquid. The obtained polymer was taken out and was dried under20 mmHg (2.66 kPa) at 70° C. for 30 hours, and 105 g of the productpolymer was obtained. The metal content in the product polymer was 70ppb.

Example 12

A polymer solution was obtained by performing the polymerization in thesame manner as in Example 11 except that a commercially availableproduct of PGMEA was used as intact. The polymer solution was passedthrough a membrane filter having 0.5 μm of pore size and then 750 g ofcommercially available methyl isobutyl ketone (MIBK) was added. At thattime, the metal content in the polymer solution was 1200 ppb.

Water washing procedure was performed by adding 1500 g of water(super-pure water) into the polymer solution, stirring and separatingthe solution. The metal content of the obtained organic layer was 250ppb. The organic layer was passed through “IONCLEAN” (trade name)(produced by Nihon Pole Ltd. the quality of material: the super highmolecular weight polyethylene of chemical modified type, the filtrationarea: 0.11 m²) constituted by a porous polyolefin membrane having acation-exchange group at 100 g/min of flow rate at room temperature.

The obtained solution was dropped into a mixed solvent of 6750 g ofhexane and 2250 g of ethyl acetate and the resulting precipitate wasrepulped with 6500 g of hexane. The supernatant was removed, the residuewas transferred to a centrifuge and the wet polymer was obtained byremoving liquid. The obtained polymer was taken out, was dried under 20mmHg (2.66 kPa) at 70° C. for 30 hours and 105 g of the product polymerwas obtained. The metal content in the product polymer was 60 ppb.

Comparative Example 5

A polymer solution was obtained by polymerizing in the same manner as inExample 11 except that a commercially available product of PGMEA wasused as intact. The polymer solution was passed through a membranefilter having 0.5 μm of pore size and then 750 g of commerciallyavailable methyl isobutyl ketone (MIBK) was added. At that time, themetal content in the polymer solution was 1200 ppb.

Water washing step was performed by adding 1500 g of water (super-purewater) into the polymer solution, stirring and separating the solution.The metal content of the obtained organic layer was 250 ppb.

Without being passed through a porous polyolefin membrane, the organiclayer was dropped into a mixed solvent of 6750 g of hexane and 2250 g ofethyl acetate and the resulting precipitate was repulped with 6500 g ofhexane. The supernatant was removed, the residue was transferred to acentrifuge and the wet polymer was obtained by removing liquid. Theobtained polymer was taken out, was dried under 20 mmHg (2.66 kPa) at70° C. for 30 hours and 103 g of the product polymer was obtained. Themetal content in the product polymer was 250 ppb.

Example 13

Production of Photoresist Polymeric Compound with Following Structure

In a reactor equipped with a stirrer, a thermometer, a refluxingcondenser, a dropping tube and a nitrogen gas introducing tube, 70 g ofpropylene glycol monomethyl ether acetate (PGMEA) was charged and afterraising the temperature to 100° C., the mixed solution containing 50 gof 5-methacryloyloxy-2,6-norbornane carbolactone (MNBL) (metal contentof 100 ppb or less), 50 g of 2-methacryloyloxy-2-methyladamantane(2-MMA), 50 g of 1-hydroxy-3-methacryloyloxyadamantane (HMA), 1.8 g ofdimethyl-2,2′-azobis(2-methylpropionate) (initiator; “V-601” produced byWako Pure Chemical Industries, Ltd.) and 530 g of PGMEA was added bydropping over 6 hours. After dropping, the resulting mixture was agedfor 2 hours and the polymer solution containing 20% by weight of thepolymeric compound represented by the above formula was obtained. Thepolymer solution was passed through a membrane filter having 0.5 μm ofpore size and then 750 g of methyl isobutyl ketone (MIBK) was added. Atthat time, the metal content in the polymer solution was 1200 ppb.

Water washing procedure was performed by adding 1500 g of water(super-pure water) into the polymer solution, stirring and separatingthe solution. The metal content of the obtained organic layer was 250ppb. The organic layer was passed through “IONCLEAN” (trade name)(produced by Nihon Pole Ltd. the quality of material: the super highmolecular weight polyethylene of chemical modified type, the filtrationarea: 0.11 m²) constituted by a porous polyolefin membrane having acation-exchange group at 100 g/min of flow rate at room temperature.

The obtained solution was dropped into a mixed solvent of 6750 g ofhexane and 2250 g of ethyl acetate and the resulting precipitate wasrepulped with 6500 g of hexane. The supernatant was removed, the residuewas transferred to a centrifuge and the wet polymer was obtained byremoving liquid. The obtained polymer was taken out, was dried under 20mmHg (2.66 kPa) at 70° C. for 30 hours and 105 g of the product polymerwas obtained. The metal content in the product polymer was 50 ppb.

Comparative Example 6

A polymer solution was obtained by performing the polymerization in thesame manner as in Example 13. The polymer solution was passed through amembrane filter having 0.5 μm of pore size and then 750 g ofcommercially available methyl isobutyl ketone (MIBK) was added. At thattime, the metal content in the polymer solution was 1200 ppb.

The polymer solution was passed through “IONCLEAN” (trade name)(produced by Nihon Pole Ltd. the quality of material: the super highmolecular weight polyethylene of chemical modified type, the filtrationarea: 0.11 m²) constituted by a porous polyolefin membrane having acation-exchange group at 100 g/min of flow rate at room temperature.

The obtained solution was dropped into a mixed solvent of 6750 g ofhexane and 2250 g of ethyl acetate and the resulting precipitate wasrepulped with 6500 g of hexane. The supernatant was removed, the residuewas transferred to a centrifuge and the wet polymer was obtained byremoving liquid. The obtained polymer was taken out, was dried under 20mmHg (2.66 kPa) at 70° C. for 30 hours and 108 g of the product polymerwas obtained. The metal content in the product polymer was 70 ppb.

Example 14

Production of Photoresist Polymeric Compound with Following Structure

In a reactor equipped with a stirrer, a thermometer, a refluxingcondenser, a dropping tube and a nitrogen gas introducing tube, 70 g ofpropylene glycol monomethyl ether acetate (PGMEA) was charged and afterraising the temperature to 100° C., the mixed solution containing 50 gof 5-methacryloyloxy-2,6-norbornane carbolactone (MNBL), 50 g of2-methacryloyloxy-2-methyladamantane (2-MMA), 50 g of1,3-dihydroxy-5-methacryloyloxyadamantane (DHMA), 1.8 g ofdimethyl-2,2′-azobis(2-methylpropionate) (initiator; “V-601” produced byWako Pure Chemical Industries, Ltd.) and 530 g of PGMEA was added bydropping over 6 hours. After dropping, the resulting mixture was agedfor 2 hours and the polymer solution containing 20% by weight of thepolymeric compound represented by the above formula. The polymersolution was passed through a membrane filter having 0.5 μm of pore sizeand then 750 g of methyl isobutyl ketone (MIBK) was added. At that time,the metal content in the polymer solution was 1200 ppb.

Water washing procedure was performed by adding 1500 g of water(super-pure water) into the polymer solution, stirring and separatingthe solution. The metal content of the obtained organic layer was 250ppb. The organic layer was passed through “IONCLEAN” (trade name)(produced by Nihon Pole Ltd. the quality of material: the super highmolecular weight polyethylene of chemical modified type, the filtrationarea: 0.11 m²) constituted by a porous polyolefin membrane having acation-exchange group at 100 g/min of flow rate at room temperature.

The obtained solution was dropped into a mixed solvent of 6750 g ofhexane and 2250 g of ethyl acetate and the resulting precipitate wasrepulped with 6500 g of hexane. The supernatant was removed, the residuewas transferred to a centrifuge and the wet polymer was obtained byremoving liquid. The obtained polymer was taken out, was dried under 20mmHg (2.66 kPa) at 70° C. for 30 hours and 105 g of the product polymerwas obtained. The metal content in the product polymer was 50 ppb.

Example 15

Production of photoresist polymeric compound with following structure

In a reactor equipped with a stirrer, a thermometer, a refluxingcondenser, a dropping tube and a nitrogen gas introducing tube, 70 g ofpropylene glycol monomethyl ether acetate (PGMEA) was charged and afterraising the temperature to 100° C., the mixed solution containing 50 gof 5-methacryloyloxy-2,6-norbornane carbolactone (MNBL) (metal contentof 100 ppb or less), 50 g of1-(1-methacryloyloxy-1-methylethyl)adamantane (IAM), 50 g of1-hydroxy-3-methacryloyloxyadamantane (HMA), 1.8 g ofdimethyl-2,2′-azobis(2-methylpropionate) (initiator; “V-601” produced byWako Pure Chemical Industries, Ltd.) and 530 g of PGMEA was added bydropping over 6 hours. After dropping, the resulting mixture was agedfor 2 hours and the polymer solution containing 20% by weight of thepolymeric compound represented by the above formula. The polymersolution was passed through a membrane filter having 0.5 μm of pore sizeand then 750 g of methyl isobutyl ketone (MIBK) was added. At that time,the metal content in the polymer solution was 1200 ppb.

Water washing procedure was performed by adding 1500 g of water(super-pure water) into the polymer solution, stirring and separatingthe solution. The metal content of the obtained organic layer was 250ppb. The organic layer was passed through “IONCLEAN” (trade name)(produced by Nihon Pole Ltd. the quality of material: the super highmolecular weight polyethylene of chemical modified type, the filtrationarea: 0.11 m²) constituted by a porous polyolefin membrane having acation-exchange group at 100 g/min of flow rate at room temperature.

The obtained solution was dropped into a mixed solvent of 6750 g ofhexane and 2250 g of ethyl acetate and the resulting precipitate wasrepulped with 6500 g of hexane. The supernatant was removed, the residuewas transferred to a centrifuge and the wet polymer was obtained byremoving liquid. The obtained polymer was taken out, was dried under 20mmHg (2.66 kPa) at 70° C. for 30 hours and 105 g of the product polymerwas obtained. The metal content in the product polymer was 50 ppb.

Evaluating Test

By dissolving 100 parts by weight of each of the polymers obtained inthe Example 11 to 15 and Comparative Examples 4 to 6 and 10 parts byweight of triphenylsulfoniumhexafluoroantimonate in ethyl lactate, aphotoresist resin composition with 20% by weight of polymerconcentration was prepared. The photoresist resin composition was spreadon a silicon wafer by the spin-coating method and a photosensitive layerwith 1.0 μm thin was formed. After pre-baking on a hot plate at 110° C.for 120 seconds, light-exposing was performed through a mask at 30mJ/cm² irradiation by using 247 nm wave-length of KrF excimer laser, andthen the substrate was post-baked at 120° C. for 60 seconds.Subsequently, the substrate was developed in 0.3 Mtetramethylammoniumhydroxide aqueous solution for 60 seconds and wasrinsed with pure water.

As a result, in case of using the polymers of Examples 11 to 15, apattern with 0.30 μm line and space was yielded. On the other hand, whenusing the polymers of Comparative Examples 4 to 6, only lost pattern wasyielded by an influence of hydrogen ion (acid) generated at the passingthrough “IONCLEAN”. Further, in the case of using the polymer ofComparative Example 5, a pattern of line and space equivalent to theExample was yielded, but an electrical characteristic was wrong becauseof large content of metal.

1. A process for producing a photoresist polymeric compound, having arepeating unit corresponding to at least one monomer selected from thegroup consisting of a monomer (a) having a lactone skeleton and amonomer (c) having an alicyclic skeleton having a hydroxyl group, andhaving another repeating unit corresponding to a monomer (b) having agroup which becomes soluble in alkali by elimination with an acid, theprocess comprising a precipitation purification step (C) ofprecipitating or re-precipitating a polymer formed by polymerization ofa mixture (I) including said monomers with a solvent being a poorsolvent, wherein the poor solvent is a mixture (II) of (i) hydrocarbons,and (ii) at least one solvent selected from the group consisting ofnitriles, ketones, esters and carbonates, wherein a mixing ratio of (i)to (ii) is 10/90 to 99/1 (volume ratio at 25° C.).
 2. The process forproducing a photoresist polymeric compound of claim 1, wherein saidpolymer is formed by polymerization of the mixture (I) including saidmonomer (a), monomer (b) and monomer (c).
 3. The process for producing aphotoresist polymeric compound of claim 1, wherein said polymer isformed by polymerization by a dropping polymerization method.
 4. Theprocess for producing a photoresist polymeric compound of claim 1,further comprising an evaporating step (H) of evaporating andconcentrating a polymer solution for removing a low-boiling-pointsolvent contained in the polymer solution, the polymer solution beingobtained by dissolving the polymer precipitated or re-precipitated inthe precipitation purification step (C) to an organic solvent.